Actually Whitworth, the 40 is everything the 10 wanted to be...successful. Try finding 10 ammo if the SHTF.
Yup, it wasn't embraced by the public like the .40 was. You can load a 10mm down to .40 but you can't go the other way. It's unfortunate that the 10mm wasn't accepted in the way its little brother was, but there is no way of predicting how the fickle public will take to a cartridge. I would still take a 10mm over the .40 irrespective of ammo availability at my local gun shop.
